Children with GHD are described as cherubic (Figs. 16-2 through 16-4). They appear younger than their chronologic age, having a rounded face, chubby limbs, and “puddling” (or dimpling) of the anterior abdominal fat. Because of their infantile appearance, further enhanced by a high-pitched reedy voice, adults may baby them or classmates may carry them around like the class pet.

FIGURE 16–2 Hypoglycemia in infancy. The larger infant had hyperinsulinism in the neonatal period, which was treated by pancreatectomy. She is shown here at age 12 months beside a very small infant of the same age who has hypoglycemia secondary to GH deficiency.

FIGURE 16–3 Crystal, showing the typical features of GHD before treatment. Inset is the growth curve after treatment with GH.

FIGURE 16–4 Crystal, 2 years later, after treatment with GH.

Examination must include careful funduscopic and visual field assessment. You can see the poorly developed muscle bulk of a child with GHD on inspection and appreciate it by running your hands over the limbs. The hair is fine and wispy, and tooth eruption is delayed. In boys, the penis may be quite small (less than 2.5 cm); remember to push the suprapubic fat pad as flat as possible, in case a normal-sized penis is merely buried in a thick fat pad.

Key Point

Height and weight percentiles (see Fig. 3–4) are usually discrepant in GHD, with a high weight-to-height ratio. This is a major clue to the need for detailed endocrine investigation. Chronic disease, especially inflammatory bowel disease, may be quite silent and manifest as short stature but, by contrast, with a low weight-to-height ratio.

When available, it is important to include the measurement of both biological parents of the child as a part of the assessment and to calculate the mid-parental height (see Chapter 3) to assess the child’s growth in the context of what would be expected for the family.

Key Point

Investigate a growth velocity of less than 5 cm per year in children age 5 years to puberty; a growth velocity of less than 4 cm per year is clearly pathologic (see Chapter 3).

You cannot assess short stature or analyze growth velocity without examining the breasts and genitalia to determine the child’s pubertal stage (see Fig. 3–9).

Chief Characteristics of Thyroid Disorders in Children

Structure, function, signs, and symptoms

Typically, the history is the most important diagnostic aid in evaluating thyroid disorders, although the physical findings serve to bolster your suspicions. Thyroid size does not reflect thyroid function. First sort out the functional state: hypothyroid, hyperthyroid, or euthyroid (normal function). Then examine the thyroid to see whether it is too big or contains any lumps and to search for associated lymphadenopathy.

Evaluating a Child with Hyperthyroidism

Symptoms of hyperthyroidism are the same in children as in adults, but it is the parents or teachers who usually complain about the child’s restlessness and irritability. The child often does not complain, although the symptoms are obvious to everyone else. The following questions will elicit the essentials:

• Has the child’s behavior changed?

• In the office setting, is the child fidgeting but trying to be attentive? This is the biggest difference in behavior between hyperthyroidism and attention deficit hyperactivity disorder (see Chapter 6).

• Has there been a recent change in performance or behavior at school?

• Has the child’s handwriting deteriorated? Tremor and involuntary muscle contractions affect the neatness of writing.

• Does the child laugh or cry more readily than before or suddenly vacillate between laughing and crying? Emotional lability is often striking in hyperthyroidism.

• Does the child throw the bedclothes off, have difficulty falling asleep, or awaken during the night?

• Is the child, particularly an older child, extremely fatigued? Restlessness and hyperactivity at the onset of hyperthyroidism may be followed by extreme fatigue.

Parents may also notice excessive sweatiness in the child, who may ask to wear light clothing only. Although loose bowel movements are often listed among the manifestations, the characteristic change is greater frequency and softer consistency of stool. If tachycardia is present, the child is rarely aware of it. A larger appetite, with either failure to gain weight or loss of weight, is also typical.

Evaluating a Child with Hypothyroidism

Like children with hyperthyroidism, children with hypothyroidism rarely complain of symptoms (Box 16–1) perhaps because the changes develop so insidiously that neither child nor parent notices the difference. When symptoms go unrecognized for years, linear growth is profoundly impaired and may be the presenting feature.

Causes of Childhood Hypothyroidism

The most common cause of hypothyroidism in childhood is autoimmune thyroiditis (Hashimoto’s disease, or lymphocytic thyroiditis). Lymphocytic infiltration causes firm diffuse enlargement of the thyroid and a pebbled surface. The anterior pituitary, sensing the lack of thyroid hormone (loss of feedback inhibition), increases the secretion of thyroid-stimulating hormone (TSH), causing the thyroid to enlarge further. Although the gland can grow in response to TSH, it cannot necessarily keep up in terms of thyroxine (T₄) production. Because the autoimmune process is destructive, some patients have a small or undetectable thyroid gland at presentation. A child with hypothyroidism secondary to hypothalamic-pituitary disease does not have thyroid enlargement (a goiter).

Congenital hypothyroidism is usually due to either absence of the thyroid or a hypoplastic thyroid that may be ectopic (located anywhere along the embryologic line of descent from the back of the tongue to the anterior neck.)

Case History 2

History. Shauna, age 15 years, says, “I was the tallest in my class in fifth grade, but I have not grown since then, and my periods haven’t started” (Fig. 16–5).

FIGURE 16–5 A, Shauna with the typical facial features of profound hypothyroidism. Note the puffy face and neck and the coarse, dry hair. B, Shauna after 4 months of treatment with thyroid hormone.

Your physical examination reveals all of the physical findings for hypothyroidism that are listed in Table 16–1. You particularly note the characteristic puffiness around Shauna’s upper face and eyes. In this case, because of profound hypothyroidism, there is also a more generalized swelling, including the neck.

TABLE 16–1 Causes of Precocious Puberty

Type of Precocious Puberty	Underlying Cause
Central	Idiopathic Hypothalamic hamartoma Germinoma (pinealoma) Other cerebral tumors or malformations Severe hypothyroidism Secondary to cranial irradiation
Gonadal	Benign precocious thelarche (? central) Ovarian cysts, benign McCune-Albright syndrome (polyostotic fibrous dysplasia of bone, ovarian cysts, large irregular café-au-lait spots) Leydig cell hyperplasia (familial testotoxicosis) Gonadal tumors (male and female) Isolated premature menses (? central)
Adrenal	Benign premature adrenarche Congenital adrenal hyperplasia Adrenal tumors
Iatrogenic	Exogenous sources

With treatment for hypothyroidism, Shauna’s menses start almost immediately. She grows an inch and loses 4 kg (9 lb) during 4 months of therapy.

In a few infants, hypothyroidism is caused by a congenital enzyme defect in thyroid hormonogenesis. In such instances, a goiter is present. In many countries, congenital hypothyroidism is now detected in the presymptomatic stage, before any significant intellectual deficit occurs, through blood spot screening between the second and fifth days of life. If congenital hypothyroidism is left untreated, the clinical manifestations may not become fully apparent until around the third month of life.

Key Point

Thyroid hormone is essential for adequate development of brain cell function and interneuronal connections. With absence of the hormone over the first few months of life, the infant suffers marked and irreversible developmental delay, the magnitude of the intellectual deficit increasing with each passing week. Universal newborn screening for hypothyroidism is therefore essential.

The infant with untreated congenital hypothyroidism has a low core body temperature, slow pulse rate, prolonged neonatal jaundice (because of poor hepatic conjugation of bilirubin), dry skin and hair, a large posterior fontanel (greater than 0.5 cm), poor head control, poor muscle tone, an enlarged tongue, a characteristically puffy face, and a hoarse cry (Fig. 16–6). The parents may report poor feeding and constipation. If acquired hypothyroidism develops after age 2 or 3 years, no permanent intellectual deficit is thought to occur.

FIGURE 16–6 Typical appearance of congenital hypothyroidism in a 3-month-old baby.

Acquired hypothyroidism must be ruled out in any child with unexplained growth retardation. The child’s appetite is generally diminished, yet there is a modest weight gain, leading to a decrease in height-to-weight ratio. Such children are not massively obese; by contrast, prepubertal obese children generally grow well in height. Constipation is a common feature. In children with type 1 diabetes mel litus, you must always rule out the coexistence of autoimmune thyroid disease, usually lymphocytic thyroiditis, because these disorders are commonly related.

Approach to the Physical Examination of the Child with a Thyroid Disorder

As with other pediatric examinations, always begin with the hands-off approach. Children are often ticklish, and touching the neck may elicit giggles and squirming, making it difficult to see the thyroid. Sit the child on a chair or examining table, with good light and in a relaxed atmosphere. If the child is old enough and cooperative, ask him or her to take a sip of water, first hold the water in the mouth without swallowing, and then swallow. Observe the area just above the sternal notch to see whether the small thyroid gland moves up and down during swallowing (Fig. 16–7). Next, ask the child to hyperextend the neck. This maneuver makes thyroid enlargement more obvious, and sometimes it is the only way to see the gland easily.

FIGURE 16–7 Demonstration of thyroid enlargement in a 12-year-old girl with a nodule in the right lobe. A, Little is visible at rest. B, The enlarged right lobe moves upward and becomes more obvious with swallowing. C, With neck extension, it is readily visible. D, Palpation of the nodule from the front.

Examining newborns and young infants

In a newborn or young infant, use a different technique to examine the thyroid. Place your hand under the child’s back, between the scapulae, and raise the baby’s shoulders, allowing the head to fall back gently until it rests on the examining table or a parent’s lap. If the thyroid is enlarged, this maneuver will expose it, allowing you to palpate with the second and third fingers of your other hand (Fig. 16–8).

FIGURE 16–8 Palpation of the thyroid gland in an infant.

Key Point

In a normal newborn, the thyroid cannot be felt. If it can be felt, it is probably enlarged.

Examining young children and adolescents

In the young child or adolescent, first observe the gland. Then, after gaining the child’s cooperation, palpate it. We generally examine from the front, as follows. Locate the cricoid cartilage, which is the smaller tracheal cartilage, just below the notched thyroid cartilage or Adam’s apple. Palpate just below the cricoid cartilage for a soft ribbon of tissue that moves with swallowing and is the normal isthmus. With practice you will become expert at finding the thyroid isthmus. Then rest both thumbs gently over the lobes of the thyroid, and ask the child to swallow. While the child swallows, move your thumbs with the child’s skin, up and down over the thyroid to outline its size. Note any nodules or irregularities you feel. You can also examine the thyroid in the traditional way, from behind the child: Place the second and third fingers of your examining hand over the gland to estimate its size, and ask the child to swallow. We often joke with older children who hate to have their necks touched that we have never choked anyone and are not allowed to!

Always measure and record the gland size so that any significant changes between visits are documented. With a measuring tape, measure from upper to lower pole and the greatest vertical dimension of the isthmus. Record the results in diagrammatic form, indicating any nodules or other irregularities.

The normal thyroid weight in grams corresponds approximately to the child’s age in years; a normal adult gland weighs 20 to 25 g and is the size of your thumb from the distal interphalangeal joint to the tip. The thyroid can be palpated in most older children. Because its normal consistency is soft, the contours can barely be seen, and the gland is rather flat when the child hyperextends the neck. Once the thyroid gland becomes firm, as in autoimmune thyroiditis (Hashimoto’s disease), or hard, as in a carcinoma, you should recognize the difference in consistency, even though enlargement may not be striking. Some carcinomas, however, may not be hard to the touch because consistency is not always a reliable diagnostic sign.

Most midline neck masses are thyroid glands or thyroid remnants. A central rounded midline mass between the thyroid and the chin is almost certain to be a thyroglossal duct cyst (Fig. 16–9), derived from a remnant of the thyroglossal duct, which runs from the foramen cecum of the tongue downward to the cricoid cartilage during fetal development. When the child sticks out the tongue, the mass moves upward. The child may present initially with an infected thyroglossal duct cyst. Sometimes, the gland fails entirely to migrate downward from the foramen cecum and manifests clinically as an oval or rounded midline mass at the base of the tongue (Fig. 16–10). This lingual thyroid usually represents all of the thyroid that the child has. Most lingual thyroids are treated with daily therapy using l-thyroxine, which suppresses pituitary thyrotropin (TSH) secretion, causing the lump to shrink markedly.